A boring and milling combined cutter and machining method for machining a boss rear end face on a workpiece

Abstract

The application discloses a boring-milling combined cutter for machining a boss rear end face on a workpiece, comprising a cutter bar (1) and a cutting part (2) arranged at the front end of the cutter bar (1), wherein the cutting part (2) is provided with an end edge and a side edge, the end edge is used for axial boring machining, and the side edge is used for radial or circumferential milling machining. The application solves the technical problem that the prior art cannot complete the machining of the whole area of the boss rear end face through one-time clamping and without tool changing, thereby reducing the machining efficiency and the surface quality.

Description

Technical Field

[0001] This invention belongs to the technical field of metal cutting tools and machining methods, specifically relating to a boring and milling composite tool and machining method for machining the rear end face of a workpiece boss. Background Technology

[0002] In the machining of housing-type parts in aerospace, precision instruments, and other fields, there is often a need for high-precision machining of the rear end face of bosses. A typical part is the 06-1 housing (reference). Figure 1 The overall structure is axially symmetric and rotates, gradually contracting from one end to the other, creating a significant size difference between the large and small openings. The large opening is open, while the small opening is semi-open. It is made of aluminum-based composite material YRZ-02, with an outline dimension of approximately φ323.85mm × 492mm and a wall thickness of 6mm. The internal cavity shape is highly complex, with stringent requirements for the positional and coaxiality of the axial and radial holes, classifying it as a large, thin-walled shell.

[0003] The housing has a slanted boss near the large end face, forming an angle of 8°52′ with the end face. A through hole (minimum diameter φ35mm) is machined on the boss. The rear end face of the boss (the side furthest from the tool entry point) is the surface to be machined, with an area of ​​approximately φ63mm², and a perpendicularity tolerance of 0.04mm to the through hole. The milling depth (i.e., machining depth) of the rear end face along the axis of the through hole is 14mm.

[0004] Regarding the processing of the aforementioned back-end surface, existing technologies mainly employ the following two solutions, both of which have significant shortcomings: The first option is machining using a coordinate boring machine (TX4163C): (See reference) Figure 2 , Figure 3 The 06-1 housing is placed on the worktable with the large end facing down, and the small end is pressed down with a pressure plate. The worktable is rotated to make the boss hole system parallel to the machine tool spindle. The center of the hole system is aligned so that the axis of the hole system coincides with the axis of the machine tool spindle. After the hole system is machined, the boring bar holder is manually obliquely installed into the φ35 hole, and then the bar holder is connected to the tool holder. After rough setting, the rear end face of the boss is machined. The main disadvantages of this method are: the manual oblique installation of the boring bar has insufficient tool setting accuracy; the thickness of the boss needs to be measured while cutting during the machining process, resulting in excessive human intervention and poor dimensional consistency; the boring bar head has a large boring area and a single feed direction, resulting in high cutting resistance, strong workpiece vibration, low machining accuracy, and rapid tool wear. Furthermore, the requirements for the straightness of the cutting edge and the perpendicularity of the cutting edge to the tool holder after sharpening are very strict.

[0005] The second option is ball end mill machining using a five-axis machining center (GS1000P): (See reference) Figure 4The shell is placed face down on the worktable, and the bottom surface of the inner cavity is pressed down with a pressure plate. The axis of the boss hole system is rotated to coincide with the axis of the machine tool spindle by rotating the worktable. After machining the hole system from the outer wall of the shell, the rear end face of the boss is machined from the inner wall of the shell using a ball end mill. The main disadvantages of this method are: clamping with the large end facing up, the clamping position is far from the machining position, resulting in large machining vibration, requiring a reduction in speed and feed, and low machining efficiency; the ball end mill machining of the rear end face of the boss is a line contact milling, which has low machining efficiency and poor surface quality; after the boss is rotated to the positive position, a negative angle is formed, which is constrained by the geometric interference between the tool and the workpiece. A cradle-type (A / C axis double swivel head) five-axis machine tool is required to achieve directional machining (3+2 positioning machining or five-axis linkage). The company only has two machine tools that meet this requirement, and the machine tool has a heavy machining workload. The equipment constraints are likely to cause the machining progress of the 06-1 shell to be delayed.

[0006] The shortcomings of existing technologies can be summarized as follows: coordinate boring methods involve a lot of human intervention, resulting in low efficiency, inconvenient measurement, high requirements for cutting tools, and long sharpening time; five-axis machining centers have insufficient clamping rigidity, low ball end milling efficiency, and poor surface finish. Neither of these two solutions can achieve the continuous machining requirement of clamping and aligning the hole system and the rear end face of the boss in a single operation.

[0007] Therefore, it is necessary to provide a new type of boring and milling composite tool and a corresponding machining method to achieve one-time clamping and one-time alignment on a conventional five-axis machining center, and to complete all machining of the rear end face of the boss at the same time, thereby improving machining efficiency while ensuring product accuracy. Summary of the Invention

[0008] The purpose of this invention is to provide a boring and milling composite tool and machining method for machining the rear end face of a boss on a workpiece, so as to solve the technical problem that the entire area of ​​the rear end face of the boss cannot be machined in one clamping without changing the tool in the prior art, resulting in low machining efficiency and poor surface quality.

[0009] To achieve the above objectives, the present invention provides a boring and milling composite tool for machining the rear end face of a boss on a workpiece, comprising: Tool holder; one end of the tool holder is connected to the machine tool spindle.

[0010] The cutting part is located at the other end of the tool holder. The cutting part has an end cutting edge and a side cutting edge. The end cutting edge is used for axial boring, and the side cutting edge is used for radial or circumferential milling. Furthermore, the cutting part is a one-piece cutter head, which has an end cutting edge and a side cutting edge.

[0011] Furthermore, the tool holder includes a main tool holder and a secondary tool holder, which are detachably connected to the main tool holder, and the cutting part is detachably mounted on the secondary tool holder.

[0012] Furthermore, the main cutter bar and the auxiliary cutter bar are connected by an anti-rotation connection structure and fixed by threaded fasteners.

[0013] Furthermore, the cutting part is a blade, which is detachably mounted on the blade holder of the secondary tool holder and fixed by threaded fasteners. The blade has an end edge and a side edge.

[0014] Furthermore, the cutting part can pass through the through hole.

[0015] In another aspect, the present invention provides a method for machining the rear end face of a boss on a workpiece, comprising the following steps: S1, connect the rear end of the tool holder of the boring and milling compound tool to the machine tool spindle; S2, clamp and position the workpiece with the boss facing down on the worktable, and press the small end of the workpiece with the pressure plate. The boss has a through hole. Align the center of the through hole so that the axis of the through hole is aligned with the axis of the machine tool spindle. S3, the front end of the boring and milling compound tool shank passes through the through hole axially, so that the cutting part reaches the machining position of the rear end face of the boss; S4, boring the near-end region of the rear end face of the boss using the end cutting edge; S5 controls the radial offset of the machine tool spindle axis relative to the through hole axis by a preset offset amount, and performs milling on the far end area of ​​the rear end face of the boss through the side cutting edge.

[0016] Furthermore, the preset offset is calculated and determined based on the target milling diameter and boring diameter of the rear end face of the boss.

[0017] Furthermore, the boss is an inclined boss, which has an angular deviation relative to the workpiece reference surface. In step S2, the machine tool spindle axis is aligned with the through hole axis by adjusting the machine tool tilt angle or tilting the workpiece during installation.

[0018] Furthermore, the workpiece is an aluminum-based composite material workpiece, and the boring and milling processes are completed continuously in one clamping of the workpiece.

[0019] Compared with the prior art, the present invention has the following beneficial effects: First, the present invention adopts a rigid and stable clamping method (the large end is placed downwards and the pressure plate presses the small end), and the boring and milling task of the rear end face of the boss can be completed in one clamping and aligning of the workpiece. After processing, the workpiece has good dimensional consistency and surface quality meets the standards, which significantly improves the processing efficiency while ensuring product accuracy. Secondly, the split structure design allows the main tool holder and the secondary tool holder to be reused. After the cutting edge wears down, only the insert needs to be replaced to continue processing, which shortens the tool change cycle and reduces tool costs. Third, the present invention adopts a regional processing strategy, dividing the rear end face of the boss into a near-end boring area and a far-end milling area for step-by-step processing. Compared with traditional full-face boring, it reduces the cutting width, lowers the cutting force, and makes the cutting process smooth, which is conducive to ensuring machining accuracy. At the same time, the tool tip performs secondary finishing on the boring surface during the milling process, which further improves the flatness and surface quality of the rear end face of the boss.

[0020] Fourth, the boring and milling composite tool and machining method of the present invention have been widely applied in various shell-type parts with inclined boss through-hole structures, verifying the practicality and reliability of the present invention, and providing important reference for the machining of the rear end face of the boss of similar structural parts. Attached Figure Description

[0021] Figure 1 This is a structural diagram showing the location of the boss through hole and the rear end face of the shell to be processed. Figure 2 This is a schematic diagram of coordinate boring machine processing; Figure 3 This is a schematic diagram of a traditional boring tool. Figure 4 Schematic diagram of the rear end face machining with a five-axis ball end mill; Figure 5 This is a schematic diagram of the boring and milling composite tool structure in Embodiment 1 of the present invention; Figure 6 This is a schematic diagram of boring and milling composite tool boring in Embodiment 1 of the present invention; Figure 7 This is a schematic diagram of milling using a boring and milling composite tool in Embodiment 1 of the present invention; Figure 8 This is a schematic diagram of the boring and milling composite tool structure in Embodiment 2 of the present invention; Among them, A-06-1 is the housing; B-the rear end face of the boss; C-the through hole; 1-the tool holder; 11-the main tool holder; 12-the secondary tool holder; 2-the cutting part; 3-the threaded fastener. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0023] This invention provides a boring and milling composite tool for machining the rear end face B of a boss on a workpiece, comprising: a tool holder 1 and a cutting part 2; the cutting part 2 is located at the front end of the tool holder 1, and the cutting part 2 has an end cutting edge and a side cutting edge, the end cutting edge being used for axial boring, and the side cutting edge being used for radial or circumferential milling; the cutting part 2 can pass through a through hole C. Example

[0024] In the first embodiment of the present invention, the cutting part 2 is detachably disposed at the front end of the tool holder 1. The cutting part 2 is an integral tool head, which has an end edge and a side edge.

[0025] For details, please refer to Figure 5 In this embodiment, the boring-milling composite tool includes a tool holder 1 and an integrated cutter head. The tool holder 1 is an integral structure made of 40Cr alloy structural steel. The integrated cutter head is made of self-ground high-speed steel strip. One end of the integrated cutter head is detachably mounted to the front end of the tool holder 1 via a four-way connection structure (i.e., an anti-rotation connection structure) and fixed with an M6 fastening bolt. The other end of the integrated cutter head is ground with an end cutting edge and a side cutting edge, which can be used for machining in two directions. The end cutting edge is used for axial boring, and the side cutting edge is used for radial or circumferential milling.

[0026] In this embodiment, the four-sided connection structure refers to a square end machined at the front end of the one-piece cutter head, with a corresponding square groove at the front end of the cutter shank. When the square end is inserted into the square groove, the cutter head cannot rotate relative to the cutter shank, thus reliably transmitting torque during cutting. Simultaneously, an M6 fastening bolt is screwed into the screw hole on the front end face of the cutter shank to tighten the square end of the one-piece cutter head, ensuring a secure fit between the cutter head and the cutter shank. This structure addresses the three requirements of anti-rotation, anti-disengagement, and quick replacement, and is simple to manufacture and reliably positioned.

[0027] In this embodiment, when assembling the integrated cutter head, the requirements for the straightness of the end cutting edge and the perpendicularity of the end cutting edge to the axis of the tool holder are not high. It is only necessary to ensure that the tip of the cutter is located at the highest position of the end cutting edge along the axial direction to meet the machining requirements. This reduces the difficulty of tool assembly and makes it easier for the boring and milling compound tool to meet the machining accuracy requirements.

[0028] The main geometric parameters of the boring and milling composite tool in this embodiment are as follows: (Refer to...) Figure 6 The straight-line distance from the tip of the integrated cutter head to the far side of the cutter shank 1 is 34mm (the straight-line distance from the tip of the integrated cutter head to the near side of the cutter shank 1 is 16mm), which is less than the minimum diameter φ35mm of the through hole C of the boss; the diameter of the cutter shank 1 is φ18mm (radius 9mm), and the distance (cutting radius) from the tip of the integrated cutter head to the axis of the cutter shank 1 is 25mm (34-9=25), which can cover the entire machining area of ​​the rear end face B of the boss.

[0029] When boring with the tool holder axis centered, refer to Figure 6 The axis of tool holder 1 coincides with the axis of through hole C, and the boring diameter is 25mm×2=50mm.

[0030] When milling with the axis offset of tool holder 1, refer to Figure 7 The radial offset of the axis of tool holder 1 relative to the axis of through hole C is preset. The offset is determined by the target milling diameter and the boring diameter, and is calculated as follows: preset offset = (target milling diameter - boring diameter) ÷ 2. Example

[0031] In this embodiment of the invention, the tool holder 1 includes a main tool holder 11 and a secondary tool holder 12. The secondary tool holder 12 is detachably connected to the front end of the main tool holder 11, and the cutting part 2 is detachably disposed on the secondary tool holder 12. The main tool holder 11 and the secondary tool holder 12 are coupled through an anti-rotation connection structure and fixed by threaded fasteners 3. Preferably, in this embodiment, the cutting part 2 is a cutting blade, which is detachably mounted on the cutting blade holder of the secondary tool holder 12 and fixed by threaded fasteners 3. The cutting blade has an end cutting edge and a side cutting edge. Both the main tool holder 11 and the secondary tool holder 12 are made of 40Cr alloy structural steel.

[0032] For details, please refer to Figure 8 In this embodiment, the boring and milling composite tool mainly consists of a main tool holder 11, a secondary tool holder 12, and inserts. The main tool holder 11 and the secondary tool holder 12 are connected by a square connection structure and fixed with M6 fastening bolts. The front end of the secondary tool holder 12 is provided with a conformal insert holder, and the insert is an APKT1604-G2 aluminum square shoulder milling insert, which is fixed to the insert holder with an M2.5 countersunk screw.

[0033] In this embodiment, the four-sided connection structure refers to the fact that a square end is machined at the front end of the secondary tool holder 12, and a corresponding square groove is opened at the front end of the main tool holder 11. After the square end is inserted into the square groove, the secondary tool holder 12 cannot rotate relative to the tool holder, thereby reliably transmitting torque during cutting. At the same time, an M6 fastening bolt is screwed into the screw hole on the front end face of the main tool holder 11 to tighten the side of the square end of the secondary tool holder 12, so that the secondary tool holder 12 is firmly assembled on the tool holder.

[0034] The main difference between Embodiment 1 and Embodiment 2 of this invention lies in the cutting part 2: In Embodiment 1, the cutting part 2 is an integral tool head, which requires re-sharpening after wear, resulting in a long cycle and high requirements for sharpening technology; in Embodiment 2, the cutting part 2 is an insert, which only needs to be replaced with a standard insert after wear to continue machining, resulting in a short tool change cycle and low tool cost. Apart from this, the boring and milling composite tool in Embodiments 1 and 2 has the same piercing capability, cutting coverage, and machining procedure. Example

[0035] Embodiment 3 of the present invention provides a method for machining the rear end face of a boss on a workpiece, referring to... Figure 6 , Figure 7 Using the aforementioned boring and milling composite tool, taking housing A (aluminum-based composite material YRZ-02 workpiece) of 06-1 as an example, the machining of the rear end face B of the boss is completed according to the following steps: S1, Insert the rear end of the tool holder 1 of the boring and milling compound tool into the spindle tool holder of the five-axis machining center (RX10) to complete the connection between the boring and milling compound tool and the machine tool spindle; S2, place the 06-1 housing A with the large end facing down on the worktable, and press the small end with the pressure plate to complete the clamping and positioning, ensuring clamping rigidity. In this embodiment, the boss is an inclined boss, and the inclined surface of the boss has an 8°52′ angular deviation relative to the reference surface of the 06-1 housing A. By using the swing angle of the machine tool A-axis and B-axis (3+2 positioning machining), the axis of the machine tool spindle is aligned with the axis of the through hole C of the boss, and the center of the through hole C is aligned so that the axis of the through hole C coincides with the axis of the machine tool spindle. S3, execute the positioning program, control the axial feed of the boring and milling compound tool, and pass the front end of the tool holder 1 through the φ35 through hole C along the axis, so that the cutting part 2 reaches the machining position of the rear end face B of the boss; the maximum radial dimension of the part of the boring and milling compound tool used to pass through the through hole C is 34mm, which is less than the minimum diameter of the through hole C φ35mm, so the hole can be successfully completed; S4, execute the boring program: At this time, the machine tool spindle axis coincides with the axis of the through hole C, and the near-end area of ​​the rear end face B of the boss is bored through the end cutting edge. The cutting radius is 25mm, the boring coverage diameter is φ50mm, and the machining of the near-end area of ​​the rear end face B of the boss is completed.

[0036] S5, Execute the milling program: Control the radial offset of the machine tool spindle axis relative to the through hole C axis by a preset offset amount. The preset offset amount is calculated according to the following formula: Preset offset = (target milling diameter - boring diameter) ÷ 2 In this embodiment, the target milling diameter is 63mm and the boring diameter is 50mm; Therefore, the preset offset is (63-50)÷2=6.5mm; After the lathe spindle is offset by 6.5mm, the side cutting edge moves along a full circular trajectory to mill the far end area of ​​the rear end face B of the boss, and then the tool is retracted.

[0037] Steps S4 and S5 are completed consecutively in the same clamping of housing A (06-1), without the need for re-alignment. Boring covers the near-end area of ​​the φ50mm boss rear end face B, and milling covers the far-end area of ​​the φ63mm boss rear end face B. Together, they cover the entire machining area of ​​the boss rear end face B.

[0038] This embodiment adopts a segmented machining strategy, dividing the rear end face B of the boss into a near-end area (the area covered by boring φ50mm) and a far-end area (the area covered by milling φ63mm) for step-by-step machining. Compared with the traditional method of boring the entire φ63mm rear end face in one go, the boring cutting width is reduced from (63-35)÷2=14mm to (50-35)÷2=7.5mm, a reduction of 6.5mm. The cutting force is reduced by nearly half, the cutting process is more stable, and the workpiece vibration is effectively reduced, which is conducive to ensuring the machining accuracy of the rear end face.

[0039] Furthermore, since the tool tip is located at the highest point in the axial direction of the end cutting edge, the surface of the near-end region after boring exhibits a slight height difference: slightly higher near the through hole C and slightly lower near the edge of φ50mm. This indicates a certain flatness error in the boring surface. During the milling process in step S5, as the tool tip moves along the full circular trajectory with the side cutting edge, it performs a secondary finishing on the bored surface, removing the raised portion. This significantly improves the overall flatness of the rear end face B of the boss and enhances the surface quality.

[0040] The aforementioned boring and milling composite tool and machining method have been applied to the machining of similar structural parts such as the 05-1 housing and 04-1 housing of a certain type of product. After machining, the thickness of the boss is consistent and the perpendicularity of the rear end face meets the tolerance requirement of 0.04mm, which verifies the practicality and reliability of the present invention.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the embodiments of the present invention have been described in detail, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of protection of the claims of the present invention.

Claims

1. A boring and milling composite tool for machining the rear end face of a boss on a workpiece, wherein a through hole (C) is provided on the boss, characterized in that, include: Tool holder (1); The cutting part (2) is located at the front end of the tool holder (1). The cutting part (2) has an end cutting edge and a side cutting edge. The end cutting edge is used for axial boring, and the side cutting edge is used for radial or circumferential milling.

2. The boring and milling composite tool for machining the rear end face of a boss on a workpiece according to claim 1, characterized in that, The cutting part (2) is detachably disposed at the front end of the tool holder (1). The cutting part (2) is an integral tool head, which has the end edge and the side edge.

3. The boring and milling composite tool for machining the rear end face of a boss on a workpiece according to claim 1, characterized in that, The tool holder (1) includes a main tool holder (11) and a secondary tool holder (12). The secondary tool holder (12) is detachably connected to the main tool holder (11), and the cutting part (2) is detachably disposed on the secondary tool holder (12).

4. The boring and milling composite tool for machining the rear end face of a boss on a workpiece according to claim 3, characterized in that, The main cutter bar (11) and the secondary cutter bar (12) are connected by an anti-rotation connection structure and fixed by a threaded fastener (3).

5. The boring and milling composite tool for machining the rear end face of a boss on a workpiece according to claim 3, characterized in that, The cutting part (2) is a blade, which is detachably mounted on the blade holder of the secondary blade (12) and fixed by threaded fasteners. The blade has the end edge and the side edge.

6. The boring and milling composite tool for machining the rear end face of a boss on a workpiece according to claim 1, characterized in that, The cutting part (2) can pass through the through hole (C).

7. A method for machining the rear end face of a boss on a workpiece, using a boring and milling composite tool as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1, connect the rear end of the tool holder (1) of the boring and milling composite tool to the machine tool spindle; S2, clamp and position the workpiece with the boss facing down on the worktable, and press the small end of the workpiece with a pressure plate. The boss is provided with a through hole (C). Align the center of the through hole (C) so that the axis of the through hole (C) is aligned with the axis of the machine tool spindle. S3, the front end of the tool holder (1) of the boring and milling compound tool passes through the through hole (C) axially, so that the cutting part (2) reaches the machining position of the rear end face (B) of the boss; S4, the rear end face (B) of the boss is boring using the end cutting edge; S5, control the machine tool spindle axis to be radially offset relative to the through hole (C) axis by a preset offset amount, and perform milling on the rear end face (B) of the boss through the side cutting edge.

8. A method for machining the rear end face of a boss on a workpiece according to claim 7, characterized in that, In step S5, the preset offset is calculated and determined based on the target milling diameter and boring diameter of the rear end face of the boss.

9. A method for machining the rear end face of a boss on a workpiece according to claim 7, characterized in that, The boss is an inclined boss, and the inclined boss has an angular deviation relative to the workpiece reference surface. In step S2, the machine tool spindle axis is aligned with the through hole (C) axis by adjusting the machine tool swing angle or tilting the workpiece during installation.

10. A method for machining the rear end face of a boss on a workpiece according to any one of claims 7 to 9, characterized in that, The workpiece is an aluminum-based composite material workpiece, and the boring and milling operations are completed continuously in one clamping of the workpiece.

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